The book "Body Language" written by Allan Pease is very widespread, but I have never seen any studies which tested explicit/implicit influence on people's perception of each other if they use gestures/postures from that repertoire. Maybe you have?
My sense is that much of Pease work is taken from researchers such as Birdwhistell (1971), Hess (1975) and the like. Knapp and Hall (1997) Nonverbal communication in Human Interaction is a more scholarly approach to the area. I would rate Kendon (2004) Gesture and Mehrabian (1972) Nonverbal communication. The latter is very frequently misquoted!
Pease's book is popular and based on rather old findings and anecdotal evidence. If you are looking for accesible introduction to the topic I recommend Patterson's book "More than words". You can find there many practical information based on experimental data.